Global greenhouse event millions of years ago led to fire-adapted trees

A new study has revealed the pre-historic moment in time some of our incredible flora became impervious to wildfires.

A DISTINCTIVE, yet mysterious evolutionary feature of many Australian plants are their fruiting 'cones', in which seeds are stored for regeneration, usually following a bushfire.

But now, according to new research this adaption to intense climates can be pinpointed to a single global greenhouse event that occurred during the mid-Cretaceous period 100 million years ago.

Head researcher Chris Mays, a palaeoclimatologist from Monash University, and his co-authors Joseph Bevitt and David Cantrill, used imaging technology— much like hospital X-rays— to observe several fossil cones sourced from Pitt Island, Zealandia that contained canals filled with fossil amber, which preserved the burnt remains of plants.

Chris said that these remains from this period point to a "fiery climate" when the average temperature was about six degrees warmer than it is today and when wild fires were far more common.

He added that because most continents during the mid-Cretaceous period were covered in forest, rich levels of oxygen and carbon dioxide intensified these wildfires.

In order to survive life in what's described in the paper as the 'Cretaceous global hothouse' several plants developed the fire-adaptive feature.

"If it had not been for the greenhouse periods of the past, we would not have many of the fire-adapted plants we see around the world today,” Chris concluded.

Patrick Baker, a palaeoclimatologist indepedent from the study praised the team of researchers for using a "neat combination" of geological fieldwork, cutting-edge imaging technology and old-fashioned botany to link a fundamental adapation to fire that is common in many conifers to a single moment in Earth's geological history.

"This is the oldest record of plant fire adaption in the southern hemisphere and highlights the role of fire in the early evoltuion of this ecologically and commercially valuable group of tree species," Patrick told Australian Geographic.

He added that the new discovery "underscores the importance of the southern hemisphere as an engine of evoltuionary innovation."